The New York Times announced plans Thursday to charge the most frequent users of its website for access, drawing mixed reactions among media analysts on its odds of succeeding.

The plan, which begins March 28 for U.S. readers, marks a new effort by one of the nation's best-read newspapers to ensure its viability in the digital age. It follows similar efforts to build pay walls by the Augusta Chronicle in Georgia and the Dallas Morning News.

The Times, which has a Sunday circulation of more than 1.3 million and has more than 30 million monthly visitors to its website, becomes the biggest non-business newspaper to attempt charging for access. The Wall Street Journal and Financial Times have long required digital readers to pay.

Pay walls are going up amid growing concern over the future of newspapers. Combined print and online advertising revenue for newspapers slid 6.3 percent in 2010, reaching a 25-year-low, according to the Newspaper Association of America.

'Important step'

"It's an important step that we hope you will see as an investment in The Times, one that will strengthen our ability to provide high-quality journalism to readers around the world and on any platform," Arthur Sulzberger Jr., the Times' publisher, wrote in a note to readers.

Under the plan, visitors to nytimes.com will be able to get free access to 20 items a month, including articles, videos and slide shows. After that, they will be asked to subscribe to one of three plans: $15 every four weeks for access to nytimes.com and a smart phone app; $20 for access to nytimes.com and a tablet computer app; or $35 for access to all three. Subscribers to the print edition will get digital access to all products at no additional charge.

Some analysts questioned whether readers would pay for news online when free articles are abundant and easily accessed on the Internet.

"What the Times is saying is, 'We're a premium news supplier, just like the Financial Times and the Wall Street Journal. Except we don't only cover the business world - we cover the entire world,' " said Ken Doctor, author of "Newsonomics" and an analyst with Outsell Inc. "They are trying to be in the category - and that's the big test here."

Getting around it

But enterprising online readers will find myriad ways through the pay wall. Within hours of the announcement, some writers were already sharing tips online about how to get around the Times' limits.

Readers can access any article by clicking links that are shared on Facebook and Twitter, for example. Readers who find articles through Google searches can read five pieces a day for free.

Metered access

But Doctor said allowing metered access to the site - charging only after a set number of visits - is a good idea for newspapers, because they can adjust the number of free articles readers can access at any time, for any reason.

If even 1 percent of the Times online readership signs up, Doctor estimates, the paper could generate $78 million in new revenue a year - significantly better than the Times' earlier effort to charge for access to its opinion pages, which generated $10 million.

But the Times' pricing is likely to scare many readers away, he said.

"My guess is they will have to test some lower pricing to get a large number of customers," Doctor said.

Felix Salmon, a business writer and blogger at Reuters, was less optimistic. He estimated it would take the Times two years just to recoup the estimated $40 million cost of developing the pay wall. In a blog post, Salmon said charging extra to access the Times through an iPad app would simply encourage more people to visit nytimes.com through the iPad's Web browser.

'Power users'

But Alan Mutter, a media consultant and former Chronicle editor, said the Times' plan probably will succeed.

"The fact is that a lot of power users of the New York Times will buy subscriptions," he said. "They're either in business or government, or they're academics or other members of the cultural elite, where knowing what's in the New York Times is mission critical."